Dravite

specimen number:
2282109

location:
Mwajanga, Simanjiro, Manyara, Tanzania

description:

A loose single crystal of dravite. In great condition.

The Mwajanga diggings, located near Komolo within the Simanjiro District of the Manyara Region in Tanzania, are localized artisanal workings renowned for producing exceptionally sharp, gem-quality tourmaline specimens. Geologically, the area is situated within the Neoproterozoic Mozambique Belt, a metamorphic terrain featuring highly evolved pegmatite veins, plagioclase-rich rocks, and magnesium-rich hydrothermal alteration zones. Small-scale artisanal specimen extraction at the Kamana pit and related surface cuts began to gain notable international prominence during the late twentieth and early twenty-first centuries as local diggers uncovered unique pockets of terminated crystals. Operating primarily as specialized, seasonal hand-mining ventures using basic manual tools, these diggings have continued to sporadically supply the global mineral market with sharp, rootbeer-brown to greenish-brown tourmaline crystals well into the twenty-first century.

Dravite is a distinct magnesium-rich mineral species belonging to the diverse tourmaline group. It typically crystallizes in trigonal prismatic forms with complex, stepped terminations, and its color profile ranges from deep golden brown and rootbeer brown to dark, near-black hues, occasionally exhibiting bicolored zones when compositional variations occur during crystal growth. The mineral commonly forms within regional metamorphic settings, particularly in contact zones where boron-bearing fluids interact with magnesium-rich host rocks like dolostones, schists, and serpentinites, serving as a durable indicator of specific geochemical environments.

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